MPP troubleshooting
Work through these checks in order when an MPP file will not upload, cannot be parsed or opens with missing information. Keep the original file unchanged while testing.
Match the message to the likely cause
| What you see | Likely cause | Next action |
|---|---|---|
| “Please choose a .mpp file” | The filename has another extension | Confirm the real source format; do not rename XML, MPX, XLSX or PDF |
| “File must be smaller than 30 MB” | The upload exceeds the viewer limit | Ask the owner to save a smaller copy or export only the required information |
| “Not a supported Microsoft Project MPP file” | The contents do not have the expected MPP compound-file signature | Download the file again or request a fresh MPP export |
| “The MPP file could not be parsed” | Password protection, corruption or an unsupported internal feature | Open a copy in the authoring application and save a fresh, unprotected MPP |
| “Parser service is unavailable” | The browser cannot reach the parsing service | Retry, then check extensions, firewall rules or another network |
1. Confirm the actual file type
Turn on filename extensions in your file manager and verify that the name ends in .mpp. A file named plan.mpp.pdf is a PDF, and changing plan.xml to plan.mpp does not convert its internal structure.
2. Check the download and file size
A zero-byte or unusually small file may be a failed download, sign-in page or cloud shortcut rather than the project itself. Download the original again and save it locally before uploading. FormatPeek accepts files up to 30 MB.
3. Rule out a browser or network problem
- Reload the page and try the file once more.
- Temporarily disable extensions that block uploads or cross-site requests.
- Try a current Chrome, Edge, Safari or Firefox release.
- If you are on a managed network, ask whether its firewall blocks the parser endpoint.
A connection problem usually affects every valid MPP file. A file-specific problem normally fails only on one project.
4. Check password protection
FormatPeek has no password-entry flow, so protected MPP files cannot be opened here. Ask the owner to remove read protection and save a separate copy. Do not send a password through an unrelated upload form or support message.
5. Create a clean copy in Microsoft Project
If the file opens in the authoring application, use Save As to create a new MPP copy under a short local path, then test that copy. When exchanging between Project versions, be aware that Microsoft warns that saving a newer file in an older version can lose newer fields or formatting. See Microsoft’s cross-version MPP guidance.
6. If the file opens but information looks different
A successful parse does not guarantee identical presentation. FormatPeek reads core schedule fields but does not load saved view formatting, custom tables, filters, groups or every custom field. Its usage and calendar screens are simplified presentations derived from extracted tasks and assignments.
- Compare task IDs, names, start and finish dates first.
- Check whether missing information lives in custom fields, formulas, notes, costs or baselines.
- Use the original Microsoft Project view for contractual or calculation-sensitive decisions.
7. What to send when reporting a problem
Do not send a confidential project file unless you are authorized. Instead, provide the exact error message, file size, browser, operating system and the Microsoft Project version that created the file. If possible, reproduce the problem with a non-sensitive sample saved by the same application.
Review the MPP compatibility details before reporting a version problem.